Being out o' collar

: : Just been reading a book about 'cockneys' just before and during the second world war. Whenever the characters talk of being out of work, the say "being out o' collar" I thought at first that it might be rhyming slang but couldn't work out what it could be. Does anyone know how the saying came about.Thanks

: I'm a cockney, although not quite born within the sound of Bow bells. I've never heard of the phrase. What's more, it's not recorded on a Cockney Rhyming Slang site http://www.cockneyrhymingslang.co.uk/
: I suspect it's made up phrase for the book. Do others know better?

I think it's a straight forward derivation based on horse/oxen collars (yokes). If you're in the collar, you're working; if you're out of collar, no such luck.